The hypophyseal portal system is a system of blood vessels in the brain that connects the hypothalamus with the anterior pituitary. Its main function is the transport and exchange of hormones to allow a fast communication between both glands. The fenestrated structure of capillaries in the hypophyseal portal system facilitates a rapid exchange between the hypothalamus and the pituitary, with only a small amount of hormones needed to stimulate an accurate effect in the respective target organs in the body.